1. Field of the Invention
This invention relates to pipes and tubular conduits and to metal working and more particularly to a mechanical process of flaring an inserted tube end or expanding a part in an aperture or radially expanding an internally fitting tube.
2. Description of the Prior Art
The prior art of metal working has known many types of tube and fitting assemblies wherein a tube and a fitting are sealed through the deformation or swaging of metal.
In many cases, the swaging or deformation process caused a cold welding of the tube and fitting due to extremely high pressures exerted between the tube and fitting. Cold welding was generally accomplished on softer materials such as aluminum and the like. One disadvantage of cold welding was that the weld took place only when the materials were freshly cut or prepared. If aluminum parts were stored for any substantial period of time, then no cold weld would form due to aluminum oxide on the surfaces.
The prior art has joined tube and fitting assemblies by inserting a tube into a fitting and using a flaring tool to expand the tubing wall to engage the fitting. For example, a fitting bore may have a recess wherein the tubing wall was radially expanded by a flaring tool to engage the bore recess to form a seal between the tube and the fitting. This process was suitable only for larger tubes and did not provide a high pressure seal.
The prior art has used a ring stake process to join a small tube to a fitting. The ring stake process incorporated a fitting having a single bore substantially the same diameter as the tube. The tube was inserted into the bore and a die swaged an outside surface of the fitting surrounding the bore to cause a deformation of the fitting to engage the tubing wall. This process did not require any internal flaring tool and provided a seal satisfactory at low-pressure so long as no torsional strain was applied between the tube and the fitting. However, the seal could be destroyed if a torque was applied between the tube and the fitting about the axis of the tube. Consequently, the ring stake tube fitting assembly proved unreliable for many applications.
In my prior application, Ser. No. 425,561 filed Dec. 17, 1973, now abandoned, I disclosed a Method and Apparatus which overcame these disadvantages. However, my prior Method and Apparatus was more adaptable for use with small tubing.
In my continuation-in-part application, now U.S. Pat. No. 3,977,710, issued Aug. 31, 1976, I disclosed a Method and an Apparatus which incorporated an auxiliary sleeve for added torsional and vibrational strength. This invention disclosed in U.S. Pat. No. 3,977,710 resulted in a seal in larger tubing which was superior to the seal formed with my original invention Ser. No. 425,561, now abandoned.
In the instant invention, I disclose a Method and an Apparatus which is more adaptable to a larger variety of tubing sizes and which results in a tube fitting assembly of superior specifications.
Therefore, an object of this invention is to provide a tube fitting assembly method which requires no cold welding nor internal flaring tools.
Another object of this invention is to provide a tube fitting assembly method incorporating a shoulder surface within a fitting orifice for preventing axial separation of the tube from the fitting.
Another object of this invention is to provide a tube fitting assembly method which can be formed from a wide range of tubing sizes and cross-sectional shapes.
Another object of this invention is to provide a tube fitting assembly method which has a high torsional strength.
Another object of this invention is to provide a tube fitting assembly method incorporating thread means for securing at least a portion of a radially expanded bead between adjacent thread surfaces.
Another object of this invention is to provide a tube fitting assembly method incorporating a plural orifice fitting for enabling radial expansion of the tubing wall in conjunction with the ring staking of an outside surface of the fitting.
Another object of this invention is to provide a tube fitting assembly method which is capable of high pressure sealing and which is reliable when subjected to vibration.
Another object of this invention is to provide a tube fitting assembly method which is applicable for use in air conditioning systems, hydraulic systems, and fluid systems for motor vehicles, aircraft and the like.